Purification of human blood platelet monoamine oxidase

Monoamine oxidase B has been purified from human blood platelets 185-fold to a specific activity of 113 nmole/min/mg protein by a combination of Triton X-100 solubilization and ion exchange chromatography. A protein fraction corresponding to 58,000 Da on sodium dodecyl sulfate-polyacrylamide gel electrophoresis was identified as monoamine oxidase by its ability to bind [3H]Pargyline.     

Purification of rat liver monoamine oxidase by octyl glucoside extraction and reconstitution

Catalytically active isoenzymes of rat liver monoamine oxidase have been copurified from the outer mitochondrial membrane by a novel method involving repetitive solubilization with octyl-β-d-glucopyranoside followed by reconstitution into lipid vesicles. As analyzed using sodium dodecyl sulfate-gel electrophoresis, the purified enzyme migrates as a single band of protein of molecular weight 60,000. The preparation is capable of metabolizing 576 nmol serotonin and 777 nmol β-phenylethylamine/min/mg protein. Apparent K_m values and sensitivity to the inhibitor clorgyline are very similar for the purified and outer mitochondrial membrane-bound enzyme when determined with the substrates β-phenylethylamine, serotonin, and tyramine.     

An autosomal genomic scan for loci linked to type II diabetes mellitus and body-mass index in Pima Indians.

Genetic factors influence the development of type II diabetes mellitus, but genetic loci for the most common forms of diabetes have not been identified. A genomic scan was conducted to identify loci linked to diabetes and body-mass index (BMI) in Pima Indians, a Native American population with a high prevalence of type II diabetes. Among 264 nuclear families containing 966 siblings, 516 autosomal markers with a median distance between adjacent markers of 6.4 cM were genotyped. Variance-components methods were used to test for linkage with an age-adjusted diabetes score and with BMI. In multipoint analyses, the strongest evidence for linkage with age-adjusted diabetes (LOD = 1.7) was on chromosome 11q, in the region that was also linked most strongly with BMI (LOD = 3.6). Bivariate linkage analyses strongly rejected both the null hypothesis of no linkage with either trait and the null hypothesis of no contribution of the locus to the covariation among the two traits. Sib-pair analyses suggest additional potential diabetes-susceptibility loci on chromosomes 1q and 7q.     

Genome-wide linkage analysis assessing parent-of-origin effects in the inheritance of birth weight

Family studies suggest that genetic variation may influence birth weight. We have assessed linkage of birth weight in a genome-wide scan in 269 Pima Indian siblings (334 sibling pairs, 92 families). As imprinting (expression of only a single copy of a gene depending on parent-of-origin), is commonly found in genes that affect fetal growth, we used a recently described modification of standard multipoint variance-component methods of linkage analysis of quantitative traits. This technique allows for comparison of linkage models that incorporate imprinting effects (in which the strength of linkage is expressed as LOD(IMP)) and models where parent-of-origin effects are not included (LOD(EQ)). Where significant evidence of linkage was present, separate contributions of alleles derived from father (LOD(FA)) or mother (LOD(MO)) to the imprinting model were estimated. Significant evidence of linkage was found on chromosome 11 (at map position 88 cM, LOD(IMP)=3.4) with evidence for imprinting (imprinting model superior, P<0.001). In this region, birth weight was linked predominantly to paternally derived alleles (LOD(FA)=4.1, LOD(MO)=0.0). An imprinted gene on chromosome 11 may influence birth weight in the Pima population. This chromosome contains one of the two major known clusters of imprinted genes in the human genome, lending biological plausibility to our findings.